Alexander's blog

By Alexander, 7 years ago, translation, In English,

Hello World.

 The next Codeforces round is prepared by me. This is my debut in arranging contests. I invite everyone to participate in the second division. I hope that all goes well. I wish you have a nice time and be able to improve your skills in programming.

 Thanks to Artem Rakhov (RAD), and Mike Mirzayanov (MikeMirzayanov) for preparation of the round and for motivation.

 Good luck and high rating!

 
 
 
 
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7 years ago, # |
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i hope this contest have an editorial as soon as possible and not be similar to CF #86 that some parts not prepared yet. and have best wish for other, thanks in advance :D

7 years ago, # |
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Nice to see a division 2 participant writing problems for division 2.
Nice move by admins. and encouragement too!! :D
  • 7 years ago, # ^ |
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    yh. This would inspire others to write good problems for contest. Really looking forward for this contest. :)

    • 7 years ago, # ^ |
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      really nice problem set. And it will encourage all. Nice move.

      And many many thanks to Alexander for this kind of beautiful problem set. :)
7 years ago, # |
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I've just noticed that no div-1 round today :(.

7 years ago, # |
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Will the competition be rated for out-of-competition participants?
7 years ago, # |
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Thanks for the problems Alexander, they were very nice! :)
  • 7 years ago, # ^ |
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    Рад что понравилось. Для меня был бесценный опыт и несколько философских размышлений.
    • 7 years ago, # ^ |
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      Some Egyptions do not understand russian, you know...
      • 7 years ago, # ^ |
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        Never mind, Google Translate was helpful. :)
        • 7 years ago, # ^ |
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          I-m sorry, I have week english skills and write English very slow.((
7 years ago, # |
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Stringy contest. :)
7 years ago, # |
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It is naughty to let letter 'Y' be a vowel and not included in the pretest :)
  • 7 years ago, # ^ |
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    also 'i' wasn't in pretest :-) in some code i seen this (not exactly this code, but it's about the bug):

    for(int i = 0; i < n; i++) {
    if(str[i] == 'a' || str[i] == 'A' || ... || str[i] == 'I' || str[i] == i)
    }

    There were all the vowels, but notice the 'i' vs i :-)

    Nice contest, thanks problemsetter!
  • 7 years ago, # ^ |
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    ha ha ha... ya,,, At first, I just saw the Example input output and understood that what would be the solution but alas I didn't notice of Y. :p

    After submitting my code I just took a look to the description and saw that Y is vowel. lollzzz... I then realized that many people did this. Thats why I hack 2 guys code. :p 
7 years ago, # |
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The constarints for problem B were so small that one could just print the pattern (only 8 patterns are there in 2-9).Made it the easiest problem
  • 7 years ago, # ^ |
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    One dude in my room did the same, and got hacked. It isn't that easy copy pasting so much of the output into the code, and not getting anything wrong. ;)
  • 7 years ago, # ^ |
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    If you "precompute" the patterns by hand, then you will waste a lot of time.
    If you "precompute" the patterns by an algorithm, then the best thing to do is to send the algorithm, not the patterns.

    The best (surely, the fastest) way to solve that problem is to generate patterns by an algorithm.

    ..And as Shuaib said, that way is also the safest!
7 years ago, # |
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i just learned to read the most obvious facts as well ..... LoL
7 years ago, # |
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7 years ago, # |
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AEIOU......Y
7 years ago, # |
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Why I can't hack pedromnasc solution of A in CF #89 room #38. In his solution he takes max array size only 110. But in answer, the array size is 198. How it gives correct answer????
It must not print more than 110 char.But it does.. HOW????
Here is  pedromnasc's. code. http://codeforces.com/contest/118/submission/741727

My input string is "CCCCCCCCCCDDDDDDDDDDQQQQQQQQQQZZZZZZZZZZLLLLLLLLLLPPPPPPPPPPbbbbbbbbbbbbbbbbbbbbggggggggggttttttttt"
Which has 99 char.
And his solution is
".c.c.c.c.c.c.c.c.c.c.d.d.d.d.d.d.d.d.d.d.q.q.q.q.q.q.q.q.q.q.z.z.z.z.z.z.z.z.z.z.l.l.l.l.l.l.l.l.l.l.p.p.p.p.p.p.p.p.p.p.b.b.b.b.b.b.b.b.b.b.b.b.b.b.b.b.b.b.b.b.g.g.g.g.g.g.g.g.g.g.t.t.t.t.t.t.t.t.t"
Which is correct. :O How??
It's length is 198, which is grater than his "aux" array size. How it obtain the "EXTRA" char (110 to 198)th char in aux[110]?? :O

I also resubmit my code only for the array size.

My question is.......
Does array size matter in CF compiler ????????

  • 7 years ago, # ^ |
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    The OS allocates memory in whole pages, usually of size 4 KB. The memory past this buffer happened to be in the same page (or another mapped page with the same permissions), and so was writable too. Perhaps the program overwrote another static variable(s), or the space could just have been unallocated by the program. Either way you can see that it worked.
7 years ago, # |
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Thanks andreyv ...It was unknown to me.

It gives me a good lesson also..   :)

7 years ago, # |
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In today's problem C, I wrote my code quickly and believed it to be right, then I submit it with G++, and it returns an "Runtime Error"

Like this:

http://codeforces.com/contest/118/submission/742856

And after some minutes, I resubmitted exactly the same code, but in MS C++

http://codeforces.com/contest/118/submission/743301

And I  passed the pretest and finally got Accepted....

Why this strange thing happens?


UPD:  I tried my two problems in "Custum Test", using the test

45 32
293440596342887581257444442930778730382520372

and still RE in G++, and AC in C++, isn't it a bug in G++ 4.6?

  • 7 years ago, # ^ |
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    Apparently your "cmp" function is against requirements for std::sort.
    If num[x] and num[y] are both equal to 0, it will always return true.
    Thus for some x and y:  cmp(x, y) && cmp(y, x) is true (which semantically means (x<y)&&(y<x)). Likely g++ compiler checks that and yields runtime error if it detects inconsistency like that.
7 years ago, # |
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7 out of the top 10 are new unrated coders...good to see that the competition is only increasing ...
7 years ago, # |
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great round :)
7 years ago, # |
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I really like the problem set.  Alexander does a great work. Nice description and finally fine problem set with logically good concept.

7 years ago, # |
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Really nice problem set thanks for this nice contest :)
7 years ago, # |
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Waiting eagerly for the editorials ....
7 years ago, # |
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what is a good solution for Problem C, brute-force seems to have passed the judge ?
i sorted all the character in the input string, and then took among them the one with highest count value(all are between '0' to '9') and then finding the distance among its closest above and down neighbours.
7 years ago, # |
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can anyone give me the link of editorials??
7 years ago, # |
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- What is the number of rated participants on Codeforces?
- It's... OVER NINE THOUSANDS!
- WHAT? OVER NINE THOUSANDS!?
7 years ago, # |
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Someone please give us Idea of solving problem C. 
7 years ago, # |
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It was a nice contest as DIV 2 contest. I wasted all the time in C where I needed to try for D. :(

Thanks to Alexander, RAD and Mike Mirzayanov for such contest. 
7 years ago, # |
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  Thanks to  Alexander'DIV2. I have a question about submit. My first submit is skipped.Why?
7 years ago, # |
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can't wait for the editorial to see the E Algorithm .. 
if someone can tell me it ... this will be highly appreciated :D